A few months ago I started using regular unleaded fuel becuase I was ticked that me 04 D2 kept running like crap and triping misfire codes and the dealer could not figure out why. I figured if it is going to run like crap I might as well use some cheaper fuel. Since I started using regular unleaded instead of premium I have had no problems and it was in the shop today for regular service and there had been no codes. I live at sea level and wonder if that has anything to do with it. Has anyone this experience?
Regular or Premium?
- Thread starter NW DISCO
- Start date
Did you get the gas at the same place? The premium gas could of had some water in it. A lot of older gas stand underground tanks can have cracks and seep water into them.
Also most tanks arent equipped with water drain off valves for the condensation build up. So if you go to a gas stand that doesn't get frequently used you will probobly get some water.
Mike
Also most tanks arent equipped with water drain off valves for the condensation build up. So if you go to a gas stand that doesn't get frequently used you will probobly get some water.
Mike
The difference between premium and regular is a difference of octane, not a difference of better or worse. Typically, your car will run best on whatever the manual says, but on older engines (or an engine with timing issues) lower octanes sometimes work better, because lower octane gas is less likely to knock.
Altitude can have a big effect on what octane works best, but my understanding is that normally lower octanes work better at higher altitudes.
If lower octanes work best in your engine, I can't think of a reason not to keep using them. Certainly better than putting in high octane so you can chase engine codes.
On the myth of "premium" gas: http://www.straightdope.com/columns/041008.html
Altitude can have a big effect on what octane works best, but my understanding is that normally lower octanes work better at higher altitudes.
If lower octanes work best in your engine, I can't think of a reason not to keep using them. Certainly better than putting in high octane so you can chase engine codes.
On the myth of "premium" gas: http://www.straightdope.com/columns/041008.html
I have purchased fuel from every place I could find. I would burn at least 3 tanks of fuel from each station and it did not matter. I understand that if the timing backs off then it will run rough with higher octane fuel, but the shop said everything was fine. My engine only has 20000 on it and has had the problem since just after I purchased it with 8000 miles. This vehicle came from Salt Lake (Land Rover Centerville). It saves me money and still seems to perform fine. I guess it is a good thing.
S
syoung
Guest
Premium fuel is less prone to knock, not low octane. Often old engines that didn't need high octane begin to require it as carbon buildup decreases the chamber volume and raises compression.
syoung said:
Correct. The octane rating really has to do with how fast the fuel burns...high octane fuel burns slower than low octane fuel.
C
Creemore
Guest
GoBruins said:
Not exactly.
Octane is not a substance, it's a property. Specifically, it is a measure of how prone fuel is to combustion under compression. Cars with high compression engines need it to prevent detonation. Old cars are thought to need it because, as someone pointed out earlier, combustion chambers would lose volume to crud buildup, effectively increasing compression. And some cars need it where the engines have been tuned with very lean fuel mixtures and advanced timing in an effort to squeeze horsepower out of a given displacement, since these things can also increase the risk of detonation or 'knocking'.
Most cars that require premium will 'run' on lower octane fuels. But they do so because they are being protected by the knock sensor, which on newer cars signals the ECU to retard timing and enrich mixture. In a lot of cases, the consequent increase in fuel consumption and the dirty exhaust cancel out the economic benefits of the cheaper fuel, and in a lot of cases they don't.
Some cars will produce more power on higher octane. Most will not. A few will even suffer from it. Car and Driver did a great piece on this a year or two ago. It is a myth that octane equals power across the board but if, for example, you drive a later model BMW, it actually does.
Finally, at least where I live, premium fuels are not differentiated only by their octane rating. They also have more additives (things like detergents and fuel line anti freeze). That's really what you're paying for, though the oil companies rarely say so (in Canada, Shell and Petro Canada advertise this, where Sunoco, for example, happily feeds the octane myth suggesting that their ethanol enhanced fuels make cars more powerful. Don't get me started on ethanol).
The fact that there is no absolute truth on this stuff is why there is always so much debate. I use premium in my 00 DII. My logic goes like this: This engine, although not powerful, has been tuned to produce way more than its original design anticipated, so score one for octane. Running clean seems to be important to keeping them reliable, so score one for additives. It doesn't have power to spare, so even if there's only one more horsepower there I want it. I get good economy on premium, so that helps. Yeah, it's 11 cents a liter more expensive than regular where I live, but if I wanted cheap truck I would have bought a Toyota. I am right. But so are the guys who refuse to pay for premium. Like everything in life, you choose your problems and choose your risks.
Just my .02. Or .11.
S
syoung
Guest
Running clean is a by product of using the proper fuel as well. Running high octane when not required results in carbon buildup, which then raises compression and then requires high octane to resist detonation. Running low octane when high is required causes the engine to alter timing to avoid knocking- which results in a less than perfect burn and loss of power.
High octane is not the "power additive" that many people think it is...
High octane is not the "power additive" that many people think it is...
higher altitude = les air
less air = less compression
less compression= less need for a slower burning flame front= less need for high octane fuels
I guess thats the new math
ok someone come tell me I'm not exactly right
less air = less compression
less compression= less need for a slower burning flame front= less need for high octane fuels
I guess thats the new math
ok someone come tell me I'm not exactly right
S
syoung
Guest
It makes sense to drop octane at higher altitudes, but I imagine on newer cars the computer compensates.
I say look in the manual. If it says premuim, use it. Especially rovers that like to crap up a lot. They love to build up deposits and sludge and have sticky valves. Those additives could be the difference between a top end job and happy motoring.
Cheers,
Kennith
I say look in the manual. If it says premuim, use it. Especially rovers that like to crap up a lot. They love to build up deposits and sludge and have sticky valves. Those additives could be the difference between a top end job and happy motoring.
Cheers,
Kennith